The chassis of a vehicle includes a structural frame and a powertrain supported by the frame. The powertrain includes a variety of components that generate and transfer power to enable an operator to drive the vehicle. Some of the components that make up the powertrain include, for example, an internal combustion engine, a transmission, a differential, and, additionally, in the case of a hybrid-electric vehicle, an invertor and an electric motor. Many of these components includes parts, such as housings or covers, that are now being manufactured from light metal alloys instead of heavier steel alloys to promote vehicle weight reduction and fuel efficiency. The particular light metal alloys currently being used are aluminum alloys and magnesium alloys.
The normal operation of a vehicle employs many different mechanical motions and interactions within the vehicle chassis to provide driving and steering capabilities. Clutches and gears are routinely engaged and disengaged, the reciprocating motion of pistons within engine block cylinders is accelerated and decelerated, and crankshafts, camshafts, and axles are rotated at varying speeds, to name but a few of the mechanical motions and interactions that regularly transpire during vehicle use. Each of these mechanical events may cause or exacerbate the reverberation of vibrations through the vehicle chassis. These vibrations can sometimes be felt and, if they fall within a particular frequency, heard by the operator of the vehicle as well as any other commuters that may be present in the passenger compartment.
Similar vibration and noise concerns have been identified in other locations of a vehicle—most notably the braking system. One approach that has been considered to alleviate the effects of braking-induced vibrations is to place a metallic or ceramic insert within a cast iron brake rotor where intense frictional interactions are experienced with selectively actuated brake pads. The metallic or ceramic insert is disposed within a cheek portion of the brake rotor so that relative interfacial frictional contact can occur between an exterior surface of the insert and an interior surface of the cheek portion during braking. This relative movement converts mechanical, oscillatory energy into thermal energy by way of friction to help subdue vibration propagation and noise generation. The cast iron brake rotor and the metallic or ceramic insert are specifically constructed to withstand the constant frictional stress applied by the nearby brake pads and the relatively high surface temperatures often generated. But this type of selective frictional stress and rapid heat generation is not typically experienced by the non-ferrous, light metal alloy parts present in the vehicle powertrain and the supporting frame.
What is needed is a simple yet effective manufacturing method for introducing a vibration damping insert into any of the non-ferrous, light metal alloy parts installed in a vehicle chassis. The role of the vibration damping insert is to alleviate the actual and/or perceived discomfort associated with vibrations and noise that emanate from the chassis during vehicle operation. A wider range of manufacturing options and more lenient material constraints are potentially available for the vibration damping insert as compared to the vibration damping work associated with a disc brake rotor braking system.